Canadian Patent

Title (French)

Appareil et necessaire de couplage d’Une suspension de motoneige

Abstract (English)

The present invention provides an apparatus and an after-market, upgrade kit constructed and arranged to be installed onto an uncoupled snowmobile suspension system that, when installed, converts the suspension system into a coupled suspension system. Specifically, the upgrade kit of the present invention is configured to be installed onto the Arctic Cat R line of snowmobiles. The upgrade kit includes a pair mounting brackets that are mounted to corresponding slide rails of the suspension system, a pair of support rods that each fixedly attach to the corresponding mounting bracket, and a pair of couplers that are pivotally interconnected to the slide rails by being pivotally mounted to the support rods.

CA 02317932 2001-05-04 APPARATUS AND KIT FOR COUPLING A SNOWMOBILE SUSPENSION Field of InventionThis invention relates to snowmobile suspension systems, and more particularly touncoupled suspension systems, and even more particularly to an apparatus, in the form of anafter-market, upgrade kit, to convert an uncoupled suspension system to a coupled suspensionsystem. Background of the Invention Tracked vehicles such as snowmobiles have rear suspension systems generallyconsisting of front and rear suspension arms pivotally mounted on shafts, which are rotatablyconnected to the frame of the snowmobile. They also include a slide frame, which comprises apair of laterally spaced apart slide rails or longitudinal skids interconnected transversely onopposing lateral sides of the machine. The slide rails are in sliding contact with an endless beltwhich contacts the snow surface contact drives the snowmobile. Front and rear suspension armspivotally interconnect the chassis to the slide frame.It is generally known in the art that independent movement of the front and rearsuspension arms is less desirable than a suspension system in which the front and rear suspensionarms are coupled. In an uncoupled suspension system, when the front suspension arm deflects asit contacts a bump, the independent rear suspension arms remains in its ride or fully extendedposition. This results in an angle of incidence between the slide rails and the bump. Unless theimpact is so large that it compresses the rear suspension arm spring and shock absorberassembly, thereby flattening the angle of incidence, the slide rails will act as a ramp forcing therear of the snowmobile upward. That is, with the slide rails angled in an upward incline due to

CA 02317932 2001-05-04the independent deflection of the front suspension arm, but not the rear suspension arm, thesnowmobile will hop over the bump, imparting a secondary jolt which increases in intensity withthe speed of the snowmobile. This secondary jolt also results in a loss of control and a reductionthe speed of the snowmobile.On the other hand, a coupled suspension system is one in which, for example, therear portion of the suspension system reacts (i. e., is coupled) to the compression experienced bythe front portion of the suspension system as the snowmobile passes over a bump in the terrain.In effect, the bump is « communicated » to the rear portion of the suspension, causing the rearportion to be pulled upward toward the chassis before the rear portion actually reaches the bump.This reduces the angle of incidence between the slide rail and the bump, which thereby reducesthe secondary jolt experienced by the rider. As a result, a coupled suspension system providesfor an improved ride because the coupled suspension is better suited to adjust to varying terrainconditions.Manufacturers have developed a variety of ways to provide coupled suspension systems,1 S which typically involve restricting the amount of longitudinal movement of the rear suspensionarm. Such system are shown in U.S. Patent Nos. 5,881,834, 5,692,579, 5,667,031, and5,944,134.Because a coupled suspension offers a superior ride than an uncoupled suspension, thoseskilled in the art of designing snowmobile suspensions have developed coupling apparatuses thatmay be added, as an after-market upgrade, to suspensions that are not coupled.

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CA 02317932 2000-09-08It is therefore the object of this invention to provide an apparatus, in the form of anafter-market, upgrade kit, :for installation onto an uncoupled snowmobile suspension systemthat, when installed, converts the uncoupled suspension system into a coupled suspensionsystem.It is further an object of the present invention to provide an apparatus, in the form ofan after-market, upgrade kit, specifically configured to be installed onto the Arctic Cat ~ lineof snowmobiles. Summary of the InventionIt is the object of the present invention, therefore, to provide an apparatus ~ and anafter-market, upgrade kit constructed and arranged to be installed onto an uncoupledsnowmobile suspension system that, when installed, converts the suspension system into acoupled suspension system. Specifically, the upgrade kit of the present invention isconfigured to be installed onto the; Arctic Cat ~ line of snowmobiles. The upgrade kitincludes a pair mounting brackets that are mounted to corresponding slide rails of thesuspension system, a pair of support rods that each fixedly attach to the correspondingmounting bracket, and a paiir of couplers that are pivotally interconnected to the slide rails bybeing pivotally mounted to the support rods.Other objects and advantages of the present invention will be realized in accordancewith the following detailed description, appended drawings, and claims. Brief Description of the Drawings The various embodiments of the present invention are shown throughout thedrawings, in which:

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CA 02317932 2000-09-08Fig. 1 is a perspective view of the preferred embodiment of the apparatus of thepresent invention after assembly but before attachment to the snowmobile suspension;Fig. 2 is a plan view of a coupler of the upgrade kit of the preferred embodiment; Fig. 3 is an end view of a wring arm tube of the upgrade kit of the preferredembodiment; Fig. 4 is a side view of the swing arm tube of Fig. 3;Fig. SA is a plan view of a flat plate of the upgrade kit of the preferred embodiment;Fig. SB is a cross-sectional side view of a flat plate of the upgrade kit of the preferredembodiment taken along section line SB-SB;Fig. 6 is a perspective view of a portion of an Arctic Cat ~ snowmobile suspensionsystem without the upgrade; kit installed;Fig. 7 is a side view of a portion of the Arctic Cat ~ snowmobile suspension systemof Fig. 6;Fig. 8 is a perspective view of the upgrade kit of the preferred embodiment installedonto the Arctic Cat ~ snowmobile suspension system of Fig. 6;Fig. 9 is a side view of the upgrade kit installed onto the Arctic Cat ~ snowmobilesuspension system of Fig. 8;Fig. 10 is a top view of the upgrade kit installed onto the Arctic Cat ~ snowmobilesuspension system of Fig. 8;Fig. 1 lA is a depiction of the; angle of incidence experienced by the slide rails as thesnowmobile passes over a bump when the suspension system in uncoupled, i.e., the upgradekit is not installed; andFig. 11B is a depiction of the angle of incidence experienced by the slide rails as thesnowmobile passes over a bump when the suspension system in coupled, i.e., the upgrade kitis installed.

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CA 02317932 2000-09-08 Detailed DescriptionReferring now more particularly to the Figures, wherein the same reference numbersare used where applicable, the apparatus of the present invention, which is also referred to asan upgrade kit, is generally indicated at 5 and is illustrated in Fig. 1. Generally, the upgradekit 5 is constructed and an-anged to be installed onto an uncoupled snowmobile suspensionsystem, so that when installed, the suspension system becomes coupled. More specifically,the upgrade kit S is configured to be assembled onto the Arctic Cat ~ line of snowmobilesthat are originally manufactured with uncoupled suspension systems, the details of which aredescribed below.Referring to the Figs. 1-5, the upgrade kit 5 comprises, among other components, twocouplers 10, two support rods 16, and two mounting brackets 22. Figures 2-4 show eachcomponent separately, and Fig. 1 shows the upgrade kit ~ assembled, but not attached to thesuspension system. The support rods are hereinafter referred to as swing arm tubes 16, andthe mounting brackets are hereinafter referred to as flat plates 22. As seen in Fig. 2, thecouplers 10 are flat oblong elements with essentially circular holes 12 formed therethrough atone end and oblong holes 14 formed therethrough at opposite ends thereof. Couplers 10 arepreferably made of an ultr;~-high molecular weight plastic, but any other suitable materialmay be used, as would be understood by those skilled in the art. The thickness of thecouplers 10 will vary deper.~ding on the material used, but the thickness is chosen to providesuitable stiffness and strength. In the preferred embodiment where ultra-high molecularweight plastic is used, the thickness of couplers 10 is approximately 0.5 inches.The upgrade kit 5 also includes the two swing arm tubes 16, an end view of which isillustrated in FIG. 3 and a :;ide view of which is shown in FIG. 4. Swing arm tubes 16 are

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CA 02317932 2000-09-08essentially cylindrical, T-shaped elements with a hexagonal stop flange 18 at one end. Swingarm tubes 16 are provided with a. threaded bore 20 dawn the center thereof for threadedplacement of a bolt 40 therein. Although the bore is shown passing through the entire swingarm tubes 16, the bore ca.r~ terminate at an intermediate position therein, as long as the borecan accommodate a bolt.When the upgrade kit 5 is assembled (Fig. 1 ), swing arm tube 16 is inserted into hole12 of coupler 10 from an end opposite stop flange 18. The stop 18, which has an averageoutside diameter greater than hole 24, limits the transverse displacement of coupler 10.When assembled, the bore of hole:. 12 of couplers 10 are in rotational, sliding contact withouter, cylindrical surfaces 30 of tlae swing arm tubes 16. The cylindrical surfaces 30 areprovided with a relatively smooth surface finish. The swing arm tubes 16 are preferablymade of a corrosion-resistant, steel alloy material or from steel that has been appropriatelytreated so that it is corrosion resistant.Referring to Fig. 5, the two :flat plates 22 are oblong elements with three holes 24, 26,and 28 formed therethrough. Holes. 26 and 28 are provided with recesses 30, 32 on one sideof plate 22 for receiving the; head of a bolt (not shown), and are used to mount the plates 22 tothe slide rails 42, which are shown in Fig. 8. Holes 24 receive bolts 25 (Fig. 1), whichengage the threaded bore f.0 of swing arm tubes 16 to thereby fixedly attach the swing armtubes thereto. Preferably, so that they do not add excessive weight to the snowmobile and sothat they provide sufficient strength to couple the suspension, plates 22 are made fromaluminum. However, any suitable material may be substituted therefor.Referring now to Figs. 6 and 7, the couplers 10, swing arm tubes 16, and aluminumplates 22 are constructed arid arranged to be assembled and attached to the sliding rails 42 ofan uncoupled snowmobile suspension system. More specifically, upgrade kit 5 is configuredto be assembled onto an t~,rctic Cat ~ snowmobile suspension system, the rear portion of

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CA 02317932 2000-09-08which is depicted, without the upgrade kit 5 attached, in Fig. 6. The suspension system of theArctic Cat ~ includes slide rails 42 that are interconnected to the snowmobile chassis (notshown) by a rear suspension arm 44. The rear suspension arm 44 is a trapezoidally-shapedstructure that includes a tra~.nsverse rear upper tube portion 46 and a transverse rear lower tubeportion 48 that are conneci:ed by tyro tubes 50 and 52. The upper tube portion 46 of the rearsuspension arm is pivotally mounted on a first transverse shaft (not shown) that is fixedlyattached to the chassis 38. Likewise, the lower tube portion 48 of the rear suspension arm 44,which extends downwardl3~ and rearwardly, is pivotally mounted on a second transverse shaft(not shown) that is fixedly attached to an end of lower arms 60 by bolts 62. Lower arms 60,in turn, are pivotally attached to the corresponding slide rails 42 by bolts 64. A shock– absorber 70 extends fronn the upper tube portion 46 of the rear suspension arm 44downwardly and forwardly to fixedly connect to a lower transverse shaft (not shown), whichis fixedly attached to slide rails 42. The suspension system further includes a frontsuspension arm (not shown) and a fiont shock absorber (not shown). As is known in the art,the Arctic Cat ~ suspension system described and shown above is uncoupled. That is, thefront and rear suspension arms move independently from one another.Referring now to Figs. 8-10, the attachment of upgrade kit 5 to the Arctic Catsuspension system will now be described. Flat plates 22 are attached to the interior of thesnowmobile slide rails 42 on either aide of the suspension, rearward of lower arms 60. In thepreferred embodiment, the flat plates 22 are fixedly attached to slide rails 42 by being boltedthereto with bolts 80 that p~~ss through corresponding through holes provided in slide rails 42.Bolts 80, nuts and lock washers (not shown) engage holes 26, 28 provided in flat plates 22.Bolts 80 may also be the Name bolts used to mount a track adjuster (not shown), which ismounted exteriorly on either side of the slide rails 42, as is known in the art. Although shownbeing bolted to the slide rails, the flat plates could also be fixedly attached thereto by other

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CA 02317932 2000-09-08fastening mechanisms, such as welding or brazing. Additionally, flat plates 22 could beintegrally formed with slidt~ rails 42, rather than being separate, distinct elements.The plastic couplers 10 are pivotally interconnected to the flat plates 22 via swing armtubes 16. Each swing army tube 16. is inserted into hole 12 of plastic couplers 10, with thestop flange 18 facing the interior of the suspension system, and fixedly connected to flat plate22 with bolts 82 and lock washers 83 (Fig. 1). Each cylindrical, swing arm tube 16 thusprovides a pivot point for plastic couplers 10 to rotate. Because the length of each swing armtube 16 is greater than the thickness of the plastic couplers 10, as best seen in Fig. 10, theplastic couplers can also slidingly translate in the transverse direction on the cylindricalsurface 30 of swing arm tribes 16. The plastic couplers 10 are then connected to the rearswing arm 44 by removing bolt 62 ;end rotating lower arm 60 so that a free end of tube 48 isexposed. Each plastic coupler 10 is slipped over tube 48 through oblong slot 14, and the rearswing arm 44 is reattached to lower arm 60.Once assembled, thf; plastic couplers 10 couple the suspension system to improve theride of the snowmobile. Prior to the installation of the upgrade kit, when the snowmobile hitsa bump, as depicted in Fig. 11 A, the front of the slide rail compresses before the rear of theslide rail, and as the slide rails 42 move upward the rear suspension arm 44 pivots about ashaft (not shown) fixedly attached b;y bolts 62. At the same time, lower arm 60 freely pivotsabout bolt 64, and this pivoting movement of lower arm 60 is not limited in either rotationdirection. Since lower arm 60 in unrestrained from rotational movement, the suspensionsystem, without the upgrade. kit installed, is uncoupled. That is, as the front of the rails hits abump, the front of the rails rise but the rear of the rails are still at the bottom of the bump,causing the rail to be presented at a specific angle of incidence 90 as the rear of the railapproaches the bump. The l;reater this angle of incidence is, the more secondary kick there is

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CA 02317932 2000-09-08to the rider when the rear hits the bv.unp and the greater the loss of control there is to the rider,and the greater loss of speed of the vehicle.With the upgrade kit 5 installed, as the front of the slide rails rise, causing rotationalmovement of the rear suspension arm 44 and lower arms 60, the lower arms 60 are restrainedfrom freely rotating due to the limitation imposed on it by plastic couplers 10. For example,as the lower arm 60 rotates clockwise as shown in Fig. 6, it engages the forward end 84 ofslots 14 and imparts a pulling force to the plastic coupler 10. Since plastic couplers 10 areinterconnected to the slidE: rails 4:2, the rear of slide rails 42 are correspondingly pulledupward, as shown in Fig. 11 B. Thus, the suspension system becomes « front to rear coupled »with the upgrade kit installed. That is, as the front of the suspension hits a bump, the front« communicates » with the rear and i:orces (or pulls) the rear upward prior to the rear actuallyhitting the bump. This causes the rail to be presented at a specific angle of incidence 92 asthe rear of the rail approached the bump, where the angle of incidence 92 (with coupling) isless than the angle of incidence 90 (without coupling). This reduction in the angle ofincidence as a result of the system being coupled with upgrade kit 5 reduces secondary kick,provides more control to the rider, and minimizes the loss of speed as the snowmobile passesover the bump.Similarly, with the upgrade kit installed, the suspension system becomes « rear tofront » coupled. Where the rider lands on the back of the snowmobile, after the rearsuspension arm 44 has displaced the’ length of slot 14 to the rear, due to the counterclockwiserotation of lower arm 60 as shown in Fig. 6, further movement and rotation are prevented bythe lower tube’s 48 engagement with a rearward end 86 of slot 14. This stopped travel in therear suspension arm 44 cau;>es the front suspension arm (not shown), and thus the front of theslide rails, to start to displace upward. Thus, the suspension system becomes coupled fromthe rear to the front. Without the upgrade kit 5 installed, where the rider lands on the back of

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CA 02317932 2000-09-08the snowmobile, the front suspension arm is independent of the rear arm and only the rearsuspension arm 44 collapses.Though not intended to be limiting, the dimensions of the components of upgrade kit5, which are sized for the P~rctic Cat ~ line of snowmobile suspensions, are the following: Table 1: Dimensions of upgrade kit components. Plastic Couplers 10 (Fig. 2) dimension (inches) L 1 2.875

The upgrade kit 5 with the above dimensions is intended for the followingArctic Cat ~ snowmobile models: the Z 440 (model years 1998 and 1999); the entire ZLseries (model years 1998-2.000); the entire ZR series (model years 1997-2000); the entireZRT series (model years 1997-2000); the Thunder Cat (model years 1998-2000); the CougarDLX (model year 1998 only); and the EXT, EFI, DLX, and 600 (model year 1998 only).

CA 02317932 2000-09-08However, as would be understood by those skilled in the art, there are potentially othersnowmobile suspensions o,n which the present invention may be used. While the invention has been described in connection with what is presentlyconsidered to be the most practical and preferred embodiments, it is to be understood that theinvention is not to be limited to the disclosed embodiments and elements, but, to the contrary,is intended to cover various modifications, combinations of features, equivalentarrangements, and equivalent elements included within the spirit and scope of the appendedclaims. Furthermore, the dimensions of features of various components provided are notmeant to be limiting, and tlae size of the components can vary from the size that is portrayedin the figures and table herein in order to accommodate differently sized suspension systemcomponents.

1. An apparatus for coupling an uncoupled snowmobile suspension, the apparatuscomprising:a pair of mounting brackets, each being adapted at one end for attachment toone of two slide rails on the snowmobile suspension;a pair of support rods, each having a stop flange at one end and beingconnected to the mounting bracket at the other end; anda pair of couplers, each defining a through hole at one end adapted to pivotallyreceive one of the support rods and defining an oblong hole therethrough at the other end.

2. The apparatus of claim 1, wherein the oblong holes in the pair of couplers pivotallyand slidably engage a rear suspension arm of the snowmobile suspension.

3. The apparatus of claim 1, wherein, as the snowmobile suspension is compressed andthe front ends of the slide rails move upward, the rear suspension arm imparts a pulling forceon the couplers from within the oblong holes to pull the mounting brackets and the slide railsupwardly, thereby coupling movement of the front and rear of the snowmobile suspension.

4. The apparatus of claim 1, wherein each mounting bracket further defines a holetherethrough at the other end, and each support rod defines a bore therein.

5. The apparatus of claim 4, further comprising a pair of fasteners, each displaceablewithin the bores in the support rods, to connect the pair of support rods to the pair ofmounting brackets through the holes in the mounting brackets.12

6. The apparatus of claim 1, wherein the couplers are made of ultra-high molecularweight plastic.

7. The apparatus of claim 1, wherein the mounting brackets are made of aluminum.

8. The apparatus of clam 1, wherein the support rods are made of a steel alloy.

9. The apparatus of claim 1, wherein the stop flanges are integrally formed with thesupport rods.

10. The apparatus of claim 5, wherein the bores in the support rods and the pair offasteners are threaded for removable engagement with one another.

11. A kit for coupling an uncoupled snowmobile suspension, the kit comprising:a pair of mounting brackets, each being constructed and arranged to beattached to one of two slide rails on the snowmobile suspension;a pair of support rods, each having a stop flange at one end, the support rodsbeing constructed and arranged to be connected to the mounting bracket at the other end; anda pair of couplers, each defining a through hole at one end and an oblong holeat the other end, the couplers being constructed and arranged to pivotally receive one of thesupport rods within the through hole.

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12. The kit of claim 11, wherein each coupler is constructed and arranged so that theoblong holes can pivotally and slidably engage a rear suspension arm of the snowmobilesuspension.

13. The kit of claim 11, wherein, when the kit is installed onto the snowmobilesuspension, as the snowmobile suspension is compressed and the front ends of the slide railsmove upward, the rear suspension arm imparts a pulling force on the couplers from within theoblong holes to pull the mounting brackets and the slide rails upwardly, thereby couplingmovement of the front and rear of the snowmobile suspension.

14. The kit of claim 11, wherein each mounting bracket further defines a holetherethrough at the other end, and each support rod defines a bore therein.

15. The kit of claim 14, further comprising a pair of fasteners, each being constructed andarranged to be displaceable within the bores in the support rods, to connect the pair of supportrods to the pair of mounting; brackets through the holes in the mounting brackets.

16. The kit of claim 11, wherein the couplers are made of ultra-high molecular weightplastic.

17. The kit of claim 11, wherein the mounting brackets are made of aluminum.

18. The kit of claim 11, wherein the support rods are made of a steel alloy.

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19. The kit of claim 11, wherein the stop flanges are integrally formed with the supportrods.

20. The kit of claim 15, wherein the bores in the support rods and the pair of fasteners arethreaded for removable engagement with one another.